@spike91 in some future video I can definitely cover that as well but it really depends on the the type of plant. Some like Anubias don't need any kind of substrate, some will only grow in planted tank soil (most of red plant species and medium/hard plants) and some can easily grow in sand/gravel (bacopa, sagitaria, limnophila etc.) This video was mostly about general explanation how they are useful in the aquarium, but if you have any specific questions about concrete plants, please just type them down 😊👌🏻